U.S. Pat. No. 3,952,151 discloses a method and apparatus for stabilizing an image produced by e.g., a camera on board a satellite, by sensing the instantaneous attitude displacement of the satellite and using these signals to adjust the image-generating beam at the ground station. The instant invention differs from the reference system in that: (1) It is a closed-loop system whereas the reference system is an open-loop system. (2) It does not require the gyroscopes needed by the reference system. Gyroscopes are heavy, consume much power, are not very accurate, have a stability and drift problem, and normally require an onboard star tracker for calibration. (3) It corrects for orbit and thermal variations as well as attitude control variations, whereas the reference system corrects for just attitude control variations. (4) It uses the camera 1, 2 itself to self-correct for errors whereas the reference system does not.
Secondary patent references are U.S. Pat. Nos. 3,223,777; 3,676,581; 3,716,669; 3,769,710; 3,859,460; 4,012,018; and 4,300,159.
The following three items give a general description of portions of the invention:
(1) D. W. Graul (one of the instant inventors), oral presentation accompanied by a posterboard display before the Environmental Research Institute of Michigan at its International Symposium on Remote Sensing of the Environment, Oct. 21, 1985; (2) "New GOES to Sharpen Severe Weather Tracking", Aviation Week and Space Technology, Dec. 23, 1985; and (3) A. Schwalb, "Envirosat-2000 Report; GOES-Next Overview", National Oceanic and Atmosptheric Administration, September, 1985 (pages 25, 26, 28, 32, 35, 36).